LU creation and deletion on EMC VMAX
A logical unit (LU) that is exported by an EMC VMAX, meaning that it is visible to a host, is either a VMAX device or a Meta device.
VMAX device
Restriction: The Storwize® V3500
system ignores an LU with a capacity of 64 MB or less.
VMAX device is an EMC term for an LU that is hosted by an EMC VMAX. These are all emulated
devices and have exactly the same characteristics. The following are the characteristics of a VMAX device:
- N cylinders
- 15 tracks per cylinder
- 64 logical blocks per track
- 512 bytes per logical block
- Hypers can be mirrored (2-way, 3-way, 4-way).
- Hypers can be formed into RAID-S groups.
Meta device
Meta device is an EMC term for a concatenated chain of EMC VMAX devices. The EMC VMAX uses a meta device to provide LUs that are larger than a hyper. Up to 255 hypers can be concatenated to form a single meta device. Using the form meta and add dev commands from the SYMCLI, you can create meta devices, which produce an extremely large LU. However, if exported to the Storwize V3500 system, only the first 1 PB are used.
Attention: Do
not extend or reduce meta devices that are used
for managed disks (MDisks). Reconfiguring a meta device that is used
for an MDisk causes unrecoverable data corruption.